Tumbler drive mechanism for dryers



Aug. 9, 1960 a. F. WALKER TUM'BLER DRIVE MECHANISM FOR DRYERS 2 Sheets-Sheet 1 Filed Oct. 29, 1958 I m r w Mia/m 1! 1 m;

Aug. 9, 1960 cs. FL WALKER 2,948,068

TUMBLER DRIVE MECHANISM FQR DRYERS Filed Oct. 29, 1958 2 Sheets-Sheet 2 raw United, States Patent TUMBLER DRIVE MECHANISM FOR DRYERS Gordon F. Walker, South Dartmouth, Mass, assignor t0 Hoyt Mfg. Corp., Westport, Conn., a corporation of Massachusetts Filed Oct. 29, 1958,'Ser. No. 770,426

2 Claims. (Cl. 3413'3) This invention relates to automatic tumbler dryers and the like and in particular it is concerned with the tumbling actionof the contents, such as clothes and the like.

Automatic clothes dryers and solvent reclaimers have found extensive use in the home and in commercial laundering establishments. The large majority of these dryers have a horizontally mounted barrel or basket into which the clothes are loaded. The basket is then rotated in order to tumble the clothes while at the same time hot air is passed over them. The drying air is generally supplied by meansof a centrifugal impeller and heated by means of electrical resistances or a gas flame.

For any given load size and cylinder diameter, there exists a precise cylinder speed of rotation for best results. That is to. say, the best tumbling action is obtained when the clothes being to fall awayfrom the wall of the basket at a point approximately 45 above the horizontal. If

the speed of the basket is too fast for the load, the clothes will cling to the outside of the basket under the influence of centrifugal force. This will cause creasing of the clothes and may subject them to damagingly high temperatures. If the speed of rotation of the basket is too slow for the load, the clothes will tumble too soon so that they do not undergo any substantial amount of free fall. The net effect in this case is that the clothes remain pretty much in the bottom half of the basket as a. close packed tangled mass which makes it impossible to dry them efficiently. To realize optimum efliciency, therefore, it follows that the speed of the basket must be changed according to the weight of the clothes and changed in such a manner as to take account of the fact that the clothes become substantially lighter during the drying process.

It is an object of the present invention, therefore, to provide for the rotation of the tumbler or basket in a rotatable dryer or reclaimer at a speed determined by the weight of the contents as measured either at the beginning of the drying cycle or at any time during the cycle.

It is a more general object to increase the efiiciency of the clothes dryer from the standpoint of the time and energy required to dry the clothes.

It is a still further object to decrease substantially the tendency of the clothes to crease during the drying operation and at the same time to impart to them a degree of flufiiness heretofore unobtainable by conventional means.

The novel features of the invention together with further objects and advantages thereof will become readily apparent from the following detailed description and the drawings to which it refers.

In the drawings:

Fig. 1 is a rear elevation of a clothes dryer and drive mechanism therefor according to the invention;

Fig. 2 is a side elevation of the dryer and drive mechanism;

Fig. 3 is a sectional view taken on line 3-3 of Fig. 1;

Figs. 4 to 6 illustrate the tumbling pattern of the clothes for different speeds of tumbler rotation; and

Figs. 7 and 8 illustrate two different positions of the Patented Aug.9', 1960 variable pitch pulley incorporated in the drive mechanism according to the invention.

From the drawing it will be observed that the dryer may be in all respects conventional but for the mechanism whereby power is transmitted for tumbling. As shown, therefore, the dryer includes an outer shell or casing 11 wherein there is supported for rotation about a horizontal axis a basket or tumbler 12. The tumbler takes the form of a perforated barrel with its open end accessible from the front of the casing. Inside the tumbler are ribs 13. The ribs project radially inwardly from the inner wall of the tumbler and are spaced uniformly around its periphery. A constant speed motor 14 is mounted near the bottom of the casing serves to furnish motive power to the tumbler and also to a fan whereby hot air is forced through it. The fan and the means for heating the air have not been shown in the drawings because they are not connected in any way with the invention and may take any conventional form.

.18 mounts the pulley 16, the shaft being journaled in bearings carried by an arm 19. There is also mounted on the shaft for rotation with the pulley 16 a planetary gear 21 in mesh with a tumbler driving gear 22 which functions as a sun gear. Sun gear 22 is rigidly mounted on a tumbler drive shaft 23 to which is pivotally joined one end of the arm 19. To the other end of the arm there is fastenedjone end of a tension spring 25 adapted to urge the arm in a clockwise direction. Tension spring 25 has its other end attached to a fixed bracket 26 projecting from the casing.

Variable pitch pulley 15 is shown in more detail in Figs. 7 and 8. As is conventional, it comprises a fixed pulley flange 31 and an axially movable flange 32. Flange 31 is made rigid with the pulley shaft 33 by a pin 34, and flange 32 has a key 35 which mates with a groove in the shaft 33 constraining it to move axially but not to rotate with respect to the shaft. A spring retaining hub 36 is mounted on the end of the shaft adjacent the pulley flange 32 and there is a compression spring 37 on the shaft having one of its ends disposed against the hub. The spring acts to urge the pulley flange 32 towards the flange 31 counter to the action of the belt on the pulley.

In operation the angular position of the arm is determined by weight of the load of clothes in the tumbler. That is to say, the greater is this weight, the more torque is required to rotate the tumbler and the greater is the tendency for the planetary gear to orbit the sun gear in a counter-clockwise direction. Spring 25 acts in a direction to oppose such movement of the arm, while spring 37 associated with the variable pitch pulley acts in aid thereof. This is because the more closely spaced are the pulley flanges, the greater is the efiective diameter of the pulley 15 which acts on the pulley 16 by tensing of the belt.

Itfollows, therefore, that for any given load, the motor pulley will assume a corresponding diameter whereby the speed of the tumbler is correctly matched to the weight of the load. For example, as the load begins to dry and become lighter, less torque will be required to drive the sun gear and hence there will be less tendency for orbital movement of the planetary gear. The result will be that clockwise movement of the arm is produced by the spring 25 which acts through the belt to force the variable pitch pulley flanges apart and decrease the effective diameter of the pulley. In this way the tumbler is slowed down to the speed at which the tumbling action is optimum, as shown diagrammatically in Fig. 4. The

result of the tumbler speed not being properly matched to the Weight of the load is shown diagrammatically in Figs. 5 and 6. In Fig. 5 the speed is too fast and in Fig. 6 it is too slow, as would be the case with any conventional constant speed tumbler. According to the invention, however, the tumbling pattern of Fig. 4 is maintained throughout a drying cycle.

Although the invention has been described in connection with a single preferred embodiment, of course variations are possible that lie within the spirit and scope of the invention. Therefore the invention should not be deemed to be limited to details of what has been described herein by way of example, but rather it should be deemed to be limited only by the scope of the appended claims.

What is claimed is:

1. In a dryer for clothes and the like having a barrelshaped tumbler for the clothes which is rotatable about a horizontal axis, and an electric motor to rotate the tumbler, the combination with said tumbler and said motor of a tumbler drive mechanism including a variable pitch pulley disposed in driven relation to the motor, said pulley being biased in the direction of maximum eflective diameter, a fixed pitch pulley mounted for rotation by said variable pitch pulley, a belt for operatively connecting the pulleys, an epicyclic gear train having a planetary gear disposed in driven relation to said fixed pitch pulley and a sun gear disposed in driving relation to the tumbler, a movable mounting arm supporting said fixed pitch pulley for limited movement thereof toward and away from said variable pitch pulley, means for moving said arm in response to orbital motion of said planetary gear, and biasing means for said mounting arm to urge said pulleys apart, thereby to decrease the effective diameter of said variable pitch pulley and decrease the speed of the tumbler as the moisture content and hence the dynamic load of the clothes decreases.

2. In a dryer for clothes and the like having a barrelshaped tumbler for the clothes which is rotatable about a horizontal axis, and an electric motor to rotate the tumbler, the combination With said tumbler and said motor of a tumbler drive mechanism including a variable pitch pulley directly driven by the motor, said pulley having a fixed flange, an axially movable flange, and means to urge said flanges together, an intermediate shaft displaced from said motorand having its axis parallel to that of the tumbler, a fixed patch pulley mounted on said intermediate shaft, a belt operatively connecting said pulleys, a planetary gear mounted on said intermediate shaft for rotation with said fixed pitch pulley, a tumbler drive shaft, a sun gear rigidly mounted on said drive shaft and being disposed in mesh with said planetary gear, a mounting arm supporting said intermediate shaft and being pivotally connected to said drive shaft to produce limited movement of said fixed pitch pulley toward and away from said variable pitch pulley in response to orbital motion of said planetary gear, and a biasing spring having one of its ends fixed and the other of its ends fastened to said mounting arm to urge said pulleys apart thereby to decrease the effective diameter of said variable pitch pulley and decrease the speed of the tumbler as the moisture content and hence the dynamic load of the clothes decreases.

References Cited in the file of this patent UNITED STATES PATENTS 1,972,377 De Laderriere Sept. 4, 1934 2,498,181 Reiter Feb. 21, 1950 2,658,399 Mercier Nov. 10, 1953 2,794,510 Mennesson June 4, 1957 "ne My: 

